This disclosure relates to relative timing and positioning measurements.
Relative positioning determines a location of a moving platform relative to one or more other platforms. Examples of moving platforms include land vehicles, ships, spacecraft, and aircraft. In some aspects, a position of a moving platform, such as an aircraft in flight, is determined relative to a non-moving platform, such as a stationary vehicle. In some instances, each of the platforms is a moving platform (e.g., two moving aircrafts or an aircraft and a ship or land vehicle).
Signals sent from respective platforms can be received and processed to determine distances between the platforms. Some techniques for determining relative positions of two or more platforms incorporate time transfer techniques, including two-way time transfer (TWTT). For example, a clock associated with each platform can record a time at which the platform sent a signal to another platform and a time at which the platform received a signal from other platform. The recorded time data can be used to calculate an offset or deviation between the clocks and to determine distances between the respective platforms and to prevent platform positioning errors due to time differences between the clocks of the respective platforms since each aircraft has two equations with two unknowns (i.e., the clock offset and the relative distance). In examples where the respective platforms are both moving, determining the relative positioning between the platforms involves consideration of parameters such as changing distances due to each platform being in motion. If these parameters are not considered, the clocks in the moving platforms may not be synchronized which can prevent the platforms from sharing data that is dependent on accurate timestamps and relative positions.